As Adam Boesel pedals an exercise bike, he sends power to a generator that converts his workout calories into electricity. Across the room in his small eco-friendly gym are half a dozen energy-efficient treadmills. On the roof, solar arrays gather more natural energy.

In Boesel's new gym, people will not only slim their waistlines, they will also shrink their carbon footprint.

Welcome to people-powered exercise for a small planet.

Boesel says the Green Microgym -- which is to open Friday in the eclectic Alberta Arts district of northeast Portland -- is the first fitness center in the country to use solar power as well as human-powered cycling and cardio machines to generate renewable energy.

The dirty secret of clean energy is that while generating it is getting easier, moving it to market is not.

“The windiest sites have not been built, because there is no way to move that electricity from there to the load centers,” he said.

The basic problem is that many transmission lines, and the connections between them, are simply too small for the amount of power companies would like to squeeze through them. The difficulty is most acute for long-distance transmission, but shows up at times even over distances of a few hundred miles.

ExxonMobil CEO and chairman Rex Tillerson defended his company's staggering $11.7 billion in profits for the second quarter, saying that the company's earnings reflected the magnitude of its business operation.

"I can understand why people are very upset and why they're very worried and concerned about their ability to deal with these high prices," Tillerson said. "It does bother me that much of that is directed at us. Our job is to provide energy, to provide it in a means that is reliable. And we hope we can provide it in a means that's convenient as well to the consumer."

Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. "This is the nirvana of what we've been talking about for years," said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. "Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon."

This could extend the driving time of electric cars and the life of mobile devices such as cell phones, music players and cameras by the same amount, making a typical laptop battery last 40 hours instead of four..

"It's not a small improvement," researcher Yi Cui said. "It's a revolutionary development."

Cui expressed optimism that the technology could be commercialized within "several years."